Sen. Elizabeth Warren may not be running for president, and she may have signed a letter encouraging Hillary Clinton to run instead, but the progressive New Englander continues to subtly undermine Clinton through omission.

First, she dodged questions last month from a local TV reporter on whether Clinton was the “best choice” for 2016. “Hillary is terrific,” is all Warren said in response. When the reporter asked the question, Warren paused before being pulled away by a supporter.

“You know, I worry a lot about the relationship between all of them: Regulators, government and Wall Street,” Warren replied.

“But what about Hillary Clinton in particular?” Couric interjected.

“Well, I worry across the board,” Warren responded.

Warren has repeatedly said she is not running for president, and she recently disavowed a draft committee set up to boost her presidential prospects. But she seems to be running for something.

Whether she wants a perch in the Senate from which to move legislation, or just a powerful voice so she can influence the national debate, Warren’s flirtations with 2016 and her less than total support for Clinton may help get her there by raising her profile and endearing liberal activists.

Later, Warren made her late-night network television debut on the “Late Show” with David Letterman. Unlike some politicians, who crack jokes or tell casual stories when they appear on late night comedy shows, Warren mostly stuck to her core message and deployed familiar anecdotes and arguments.

Even an emotional story about her family’s financial trouble (the same one she told a few hours earlier to Couric) had a policy angle – that the minimum wage is good. The only moment of real levity came when Letterman intentionally misheard something Warren said to accuse the senator of barbecuing her golden retriever.

In general, Warren said progress has been made over the past six years since the financial crisis, but that more needs to be done. She also called for reducing or eliminating the government’s profits from student loans. She did not address Clinton.